Ever wondered how those massive lorries hauling oversized loads are regulated? The Special Types General Order (STGO) is the framework that keeps abnormal loads moving safely.
By Zed Aziz
When you see a massive lorry hauling an oversized load on the motorway, you might wonder how such an enormous vehicle is regulated. One of the key frameworks is the Special Types General Order (STGO), which is crucial for the safe and efficient transport of heavy and abnormal loads.
STGO stands for Special Types General Order — a legal framework that governs the movement of heavy and oversized loads on UK public roads. These loads are often too large or heavy to be transported under standard regulations, so they require specific permissions and safety measures. The detail sits within the Road Vehicles (Construction and Use) Regulations 1986, under the Special Types General Order 2003.
Transporting heavy and oversized loads presents unique challenges. Roads, bridges and other infrastructure must be able to handle the extra weight and size. Without proper regulation, these movements could damage infrastructure, endanger other road users and disrupt traffic. STGO ensures movements are carried out safely and with minimal impact on the public.
STGO is divided into three categories based on the weight of the load.
| Category | Weight limit | Typical speed limits | Example loads |
|---|---|---|---|
| Category 1 | Up to 50,000kg (50 tonnes) | 40 mph motorway / 30 mph other roads | Large construction or agricultural machinery |
| Category 2 | Up to 80,000kg (80 tonnes) | 30 mph motorway / 20 mph other roads | Heavy industrial equipment, large prefabricated structures |
| Category 3 | Up to 150,000kg (150 tonnes) | 25 mph motorway / 20 mph other roads | Extremely large machinery, bridge sections, turbine blades |
As the weight increases, so do the requirements. Category 1 needs sufficient axles for weight distribution, route notification to police and highway authorities, appropriate markings and lighting, and trained drivers — with escort vehicles on some routes. Category 2 adds reinforced axles, more detailed route approval, specific permits, usually mandatory escorts, bridge assessments and sometimes environmental considerations. Category 3 vehicles are often custom-built, requiring detailed route surveys, multiple permits, mandatory (often multiple) escort vehicles, potential infrastructure reinforcement and community engagement for particularly disruptive moves.
A driver operating an STGO vehicle must hold a CPC (Certificate of Professional Competence) Class 1 licence, but additional training is often required given the complexity and risk of abnormal loads:
To move an abnormal load you must obtain permits from the appropriate authorities — typically National Highways (or the relevant authority for Scotland, Wales or Northern Ireland) and local highway authorities along the route — and notify the police for traffic management.
STGO compliance is complex, and getting it wrong carries real risk to your operation and your Operator Licence. If you need help with the application process or want to be sure your wider compliance is watertight, our team can guide you — book a compliance audit or contact us today.
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